1. Field of the Invention
The present invention relates to a semiconductor chip manufacturing method in which a semiconductor wafer is divided into individual semiconductor chips, and also relates to a semiconductor device including a divided individual semiconductor chip.
2. Description of the Related Art
Japanese Patent Laid-Open No. 2006-222359 describes, as an invention of this kind, a manufacturing method in which a semiconductor wafer is half cut along a dicing line from the semiconductor wafer other surface side with a dicing blade of a larger width and is thereafter full cut from the semiconductor wafer front surface side with a dicing blade of a smaller width to form individual semiconductor chips.
According to the description of this dicing method, the dicing thickness at the time of full cutting from the front surface side is reduced and, therefore, the accuracy of the dicing position is improved and the occurrence of a chip or a crack in the semiconductor chip surface is prevented.
Japanese Patent Laid-Open No. 6-232255 describes a semiconductor chip manufacturing method in which a V-groove is formed in a semiconductor wafer from the semiconductor wafer other surface side with a bevel cutting blade and the semiconductor wafer is thereafter full cut from the semiconductor wafer front surface side with a dicing blade of a width smaller than that of the V-groove.
In recent years, semiconductor devices, such as display devices exemplified by semiconductor devices for liquid crystal display drivers, have been developed in which the aspect ratio of the one surface of a semiconductor chip is high. If the aspect ratio of the one surface of a semiconductor chip is increased so that the entire chip is elongated, the semiconductor chip becomes easily crackable by an external force such as a bending or torsional force. In such a case, a desirable mechanical strength of the chip is secured by securing a comparatively large size in thickness. For example, the shorter-side size of the one surface of a semiconductor chip, for example, in a semiconductor device for a liquid crystal display driver is about 800 μm while the size in thickness is large, about 400 to 700 μm.
In dicing a semiconductor wafer, there is a need to set the thickness of the edge of a dicing blade equal to or larger than a certain value. This is because, if the edge thickness is equal to or larger than a certain value with respect to the dicing depth (edge projection amount), the edge bends to such an extent that dicing cannot be correctly performed.
Each of the semiconductor manufacturing methods described in the above-mentioned patent documents therefore entails a limitation to the reduction in thickness of the edge of a dicing blade for full cutting a half-cut semiconductor wafer from the wafer front surface side.
With respect to semiconductor devices and optical waveguide devices in recent years, there is a demand for improving the yield of semiconductor chips in a semiconductor wafer by reducing the thickness of dicing lines provided on the semiconductor wafer.